Problem: $ F = \left[\begin{array}{rrr}2 & 2 & 0 \\ 2 & 2 & 1 \\ 0 & 2 & 1\end{array}\right]$ What is $ F^{-1}$ ?
Explanation: $ = \left[\begin{array}{rrr}0 & \frac{1}{2} & -\frac{1}{2} \\ \frac{1}{2} & -\frac{1}{2} & \frac{1}{2} \\ -1 & 1 & 0\end{array}\right]$